Life Drain / Drain Life: Works on Undead &...?

[Huntsman]

Graeme Dice said:Only lifeless undead are lifeless. Life draining attacks will still cause full damage to these, but will not cause and fatigue or health gain.

Let me make sure I got this straight...

If I have a Wraith Lord with Soul Vortex on and he attacks a unit flagged as Undead but not Lifeless (e.g Tartarian Titan), the SV will both a) cause full drain damage and b) give health and fatigue back to the Wraith Lord?

OTOH, if he attacks a Lifeless being (e.g. Iron Dragon) the SV will only cause full drain damage but it will not give health/fatigue back to the WL?

Right? Whew...